bbm problems

I have had a blackberry 3 years now and lived in an area with dodgy signal. At home no matter what network you cant get a signal this has not bothered me as i connect to wifi and use bbm this has been good when my husband works away we can always keep in contact but today it wont send any more its ok if i take a drive in my car and find a signal but soon i as i go to use wifi it wont work. its worked fine over the past 3 yrs untill today anyone know why this is